A Novel Linear Relationship for Calculating Dynamic Shear Modulus of Geomaterials

The dynamic shear modulus G of soil was determined using a dynamic triaxial test system (DTTS) together with a fitting method. First, a novel linear relationship between G and damping ratio lambda was proposed, which was used to select the appropriate G. Then, a hyperbolic model was constructed using the optimized parameters a and b representing the intercept and slope, respectively, from the linear regression of 1/G and dynamic shear strain gamma(d). Finally, the differences between the tested and predicted results for G were analyzed for different soil types. The experimental results show that this linear relationship can overcome the shortcomings of the nonlinear relationship found in the large deformation stage and can predict lambda in the hysteresis loop that is not closed case. In addition to Baoji loess, G was slightly larger (10%) than the experimental curve in the elasto-plastic stage; however, the experimental results show that the attenuation curve of G for Baoji loess is greater than the calculated value in the elasto-plastic stage. The test and analysis results will improve the knowledge of the dynamic properties of soils and also provide reliable values of G for further evaluation of seismic safety at engineering sites.